Bristle worms are not going to eat your live rock, they might make some tunnels but it doesn't hurt that much. If you are having such a huge amount of them it is only because they have enough to eat and breed. You might be overfeeding or something died (not always but just a maybe).
I found out that Arrow crabs will eat fairly small bristle worms of any type. Not the huge jumbos but hey I have devised a devilish trap for them that catches them and is SUPER cheap!!!!!
Get a small tuperwear (like an old clean creamcheese container)
Not clear so wormies can't see the food inside.
Put a mixture of some food inside, raw clam, cooked but fresh shrimp, raw "human type fish" That we would eat.
use a razor blade and cut an X into the center of lid of Trap
Slightly smaller than you expect worm to be.
push corners of X in so wormies can enter...BUT they can't leave (if X is correct size) because the X pushes out against them and traps them if they try to leave.
YEAH, worked for me and is CHEAP CHEAP CHEAP
