ZDDP, is Zinc Dialkyl Dithio Phosphate,
in english it is a anti wear additive, whose level has been lowered over the years, it is a amazing anti scuff additive put in oils and was the "cure" for OHC wear issues formulated years ago for this exact problem, you can but bottle of ZDDP to add to your oil.
The reduction in ZDDP has come about for many reasons, mainly environmental, but with ever better oils it's use in most engines was not so necessary in the concentration used, unfortunately there are exceptions like the CVH cam cruncher.
From personal use I can recommend ZDDP plus as a good additive.
Another option would be to stop wasting money on oils that are fossil fuel based, filling with synlube, would stop a lot of the wear, it is ONCE only oil fill, proved the world over since the early 70's, but is costly, around £250-£300 to fill the sump.
Failing that look at "classic" fully synthetic oils, they may contain elevated ZDDP.
tabetha