Pretty Boat! I would love to here how it performs in surf.
As far as the wear, I would suggest that you stop/minimize dragging the boat. Regardless what a kayak is made of, repeaded dragging will wear away the stern. I like to grab the boat by the cockpit and carry it against my hip just far enough that I can get a cart under the stern.
Like Laszlo, I have had good luck with the dynel rub strip kit. I used it on the first 5 boats and it has held up well. When it get a little worn, I build it back up with more epoxy/graphite mixture. The negatives are that it adds weight and takes a bit of time/careful masking to make it look nice.
On my latest build, I decided to try a different product, called KeelEazy. It is a thick plastic backed with adhesive that you apply with a heat gun. This product has worked very well on protecting the shear of my racing boat from paddle strikes. My success on the keel of the Frej has been mixed. It adheres well where the keel is mostly flat but not where the bow/stern have sharp bends. If you look closely at the bottom pict, you will see that the rub strip stops where the bow curves more sharply upward. I could not get it to lay flat and stick farther up the curve. Overall, I still beleive that the dynel is the best approach, but is areas without sharp curves, KeelEazy may be a quick and easy alternative.