Sandpaper and appliance touch up paint depending on how bad it is, or you can buy just a new lid

sandpaper it until it's smooth, then use touch up paint unless it's real bad

When I first moved into my house, I bought a washer off my grandmother. It was pretty rusty, so I did what the above posters suggested and used sandpaper to smooth the area and then painted it. It worked pretty well, so I would give that a try. I didn't have any more rust problems after that, but eventually bought a new washer and dryer because I wanted something that was more energy efficient.