Getting bumps/warts on surface, Cura doesn't want to comb?

I have not been able to print smooth and round shapes using Cura 3.3.1 (or earlier) without bumps. I think they are seams? The filament is PLA.

Combing is enabled, which I thought makes it so that the nozzle travels over already printed areas, instead of flying over the air...right?

I have been able to keep the seems hidden for the most part when there are sharp corners. Sometimes cura hides the seems properly...sometimes it doesn't.

Here is an example shape I have tried printing with several different settings:

The object above was printed using "random" seam corner preference. If I had chosen "sharpest corner", the bumps would all just stack up in one place, but still stick out.

Just look at the travel lines below! Why is it jumping all over the place?

I have tried "Avoid printed parts when traveling" enabled and disabled, doesn't seem to make much difference.

I feel that there should be a configuration that results in the nozzle not jumping through the air like that, but I can't find it. Perhaps that's not related to the bumps?

The printer is a MonoPrice Mini Delta.