The rack is lubed by the fluid, but, not having a pump will not create additional wear in the rack. If there is a rag joint, that is where you will see wear, but it will likely take years and years and years to see it.
I ran well over a year without it. I just pulled the belt. I gave the pump a spin or 2 every few months or so by hand, and added a few ounces of fluid every now and then to keep it all wet. When I replaced the rack, I filled up the pump, put on a belt and it all works fine to this day.
Oh, did I mention I used to rebuild racks, boxes and pumps.
You will not hurt it as long as there is enough fluid around to keep the seals wet/lubricated and the rust out.