Kevlar Felt Skid Plates – thefeltstore.com
A Kevlar felt skid plate will stop abrasion on the stem better than just about any material on the planet. The stuff feels like thick chamois shirt fabric and you apply it using epoxy resin, saturating it as you would fiberglass. It's not possible to sand it, so the neatest application that you can do is advised and if you are aware of the target area from previous beachings, there is no reason to make the "grunch patch" (technical term in the canoe industry) any bigger than you have to.
Paint-wise, I have used Brightside, EasyPoxy and hardware store polyurethane floor enamel all with decent results - usually rolling and tipping.