I expect they are referring to the total life of the parts. While the harder surfaces should stand up in a competition application (X # of passes, Y # of laps, ...) it's unlikely they will last tens of thousands of miles anyone with a street engine is likely to expect. As for a different material, ask your local welding supplier about "hard face" it's designed to put metal on earth movers (buckets, blades, etc) so it wears longer. It should stand up to a lubricated tappet, being able to grind it to shape as a cam lobe? Dunno.