A "bump" to me is when you're chugging along making minor changes--switching articles, adding and subtracting pesky commas, weighing options to the universally-shunned adverbs that spring up like weeds in a garden--and then, suddenly...a bump, the thing in the writing itself that stops your progress cold, or at least redirects it. Maybe you missed some plot point. Maybe what should have been a minor character steps forward and does something major, requiring backstory or at least more page time. Or maybe you've got an entire section that is not only not important to the plot, but possibly the work of your evil twin who might have been hopped up on medication and suffering a psychotic break when he wrote it. If it's the latter, your work is easy: hack it out and either toss it or save it for a future story. If it's one of the others, well, you've got some major rewriting to do.
Now, this isn't a bad thing. Not at all. Finding these bumps and fixing them are, after all, what rewriting is about, and can only make your work stronger. But of course this is going to add more time and effort, ranging from mildly inconvenient to soul-shatteringly disheartening depending on the severity of the problem. In my case, I realized that I had written nearly half the book talking about this darkness inside the main character, hinting at this past event that had caused it, without devoting a single page to it. I needed, I realized, to have that story much sooner, and it wasn't going to be a matter of simply cutting those scenes from later in the book and pasting them earlier. It's going to be a major rewrite, after which, I will go through the rest of the book, and then re-read the whole thing again, seeing if the new stuff works well enough with the rest.
But it's all good, folks. I wanted to have more of the work done, by now, sure. But I know that I'm making the story better. My goal as a writer is to write something that hooks the reader, drags them into the story, and then makes them forget that they are reading. It only takes "Wait, what?" moment to snatch the reader out of the story. Too many of those, and whether the reader bothers to finish your story or not, the likelihood of them picking up your next book are slim to none.
So do the work. Rewriting and editing can be a drag, but they are essential to making your book the best it can possibly be. Hire a professional editor to go through it if you need to (and if you're self-publishing, you should do that anyway; possibly, even if you are going through a traditional publisher!), and work with them to make your book better. (Just one caveat: take what time you need to make the work the best you can make it, but know when you're done. Perfection is impossible, and at some point, you're going to have to get the book out there, or you'll never have a career. As the King said to the White Rabbit in Alice in Wonderland: "Begin at the beginning and go on till you come to the end: then stop.")
Put in work, my people. Put in work, and you'll produce something that people will remember and talk about. And maybe recommend. You want that, don't you?