There aren't any metal plugs, but you can get them filled in. can either use metal and have them welded, but you'll have to remove the carpets. Or you can use fibreglass matting, but you'll need to clean the area around there to enable the matting and resin to bond. Or you could just remover the existing plugs, treat the rust with an inhibitor, then paint with fresh undersell, and finally put some fresh plugs. Whichever route you chose, not that difficult a job.