Melanurus wrasse are good two. Most reef wrasses will take care of such pests and are easy to keep after the worms are gone while the nudi really isn't.
The nudi is gonna starve when there's no worms left. A 6 line would be fine in a 20g. As for the pods, if you have a fuge there will always be some in there.
unfortunately most of the worms are in the fuge so they would just continue re-infesting. Anyone ever had success with mandarins? I wanted some anyway. That's why I wanted lots of pods.