Rust stains are virtually impossible to remove. I ruined some brilliant white t-shirts that way, even bleach didn't help. Sorry to give you bad news....the other thing is get some new pegs. And I'm not being rude its the only option to prevent further problems.
Im not being silly here, but as a last resort before throwing them away try soaking them in WD40 to see if that removes it.
Im an engineer and i know that the WD will wash out, lets just hope it takes the rust out first !.