I became tired of having to replace these pads every year. Instead of replacing them again, I decided to make a more durable guide cover.
I bought 3" PVC pipe, capped it, painted it black, and then covered it with black carpet. I used Gorilla glue to keep the carpet on the PVC. The total cost was around $30. They have lasted the last 2 years and are still going strong. The 3" pipe rolls when the boat's rub rail hits it, so no damage is done to the rub rail or the guides what so ever.
Here's a pic (kind of hard to see, but you get the idea):