Sorry I didn't answer you earlier tom e but I honestly don't know if they'll make snack of your nerites.
But as Brian said anything small and slow enough is most likely fair game. I have personally seen my assassins eating shrimp. I cannot however tell you if the shrimp was already dead or dying. I have witnessed at least 6 Red Cherries, 3 Blue Shrimp AKA Blackberry Shrimp, and about 6 Yellow Shrimp being eaten by the assassins. All in different tanks and all had other snail species in them.