This can be a problem with pickups molded out of a inexpensive high pressure styrene plastic. Bobbins should last many years and I’ve seen only one Gibson pickup worn out because the player used a metal pick. You could use a epoxy based coating over the end of the bobbin but it might make it look pretty bad. You could paint the surface with a clear finish to coat the coil and build up the surface of bobbin. It might be best to use a cover to protect the coil from further damage. I would also suggest sending the pickup back to the manufacturer and have him rebuild it with new parts. I am often rebuilding various types of pickups and doing custom modifications.