Hard to say if they are rotten or not. How did you come to the conclusion that earthworms are eating the roots? Did you see them eating the roots? Did you pull the plant up to see the roots being devoured? If they are rotten then it could be another cause for that like overwatered pot.

Earthworms don't eat plant roots. They eat decaying organic matter. Earthworms are very beneficial for plants. They aerate the soil and their castings provide fertilizer.

Deanna