Will they over-run my tank?
They shouldn't. They eat detritus and other organic material that gets wedged inside your rocks, in essence keeping your tank much cleaner than not having them.
If you're super concerned, pluck out the really big ones when you see them or get a six line wrasse, they will pluck at them.
Will they over-run my tank?
IME, the more you over feed, the more food for them there is, and the more worms there will be. I used to have a ton of bristle worms, and now i can hardly find one, dont know what got rid of them, but there gone now.