With super low wear numbers like you're showing (lead, especially) and no potassium (I'm not 100% sure that the coolant you're using doesn't have potassium in it) I'm going to doubt that you've got much, if any coolant leak into the engine. Have you noticed the coolant level dropping?
I'm going to wager that the very low wear is the result of a lot of driving (more highway miles vs. lots of cold starts and short trips) and a well-seasoned engine that's wearing well.