JD is right about teflon being the ultimate. Problem is, they don't make one for your rest that I know of. The best course of action right now is to clean the rod with alcohol, and the slide as much as you can (you got that dumb cable attached that raises the rest). Just move the slide back and forth while cleaning the rod to get as much grit out as possible. This should take care of the problem. In the meantime call NAP and ask them to send you a new slide.

Do not lube the rod with any oil based lubricant. Oils will just give any dust or grit something to attach to and compound the problem. Possibly you could try a silicon spray or graphite. In any case you should clean your rod more often. Even dust can mess things up.

I wonder how one of those silicon rags for gun cleaning would work.