I was doing some reading on ceramic seals (
one example was this link about ceramic engineering and properties)and their need for antifreeze and I was not able to find anything saying that the seals "required" a liquid lubricant during operation, only during assembly. My thinking would be that if antifreeze was able to lubricate the surface between the shaft and the ceramic, then by nature, that would mean your pump was leaking "lubricant" or antifreeze past the seal and therefore wouldn't be leakless anymore.
I do like to run antifreeze in my cars though to hopefully cut down on rust forming in the block, so it may also help to prolong the life of the coolant side of the pump.
I found that they are widely used in pumps for water, more specifically in hot tubs, which do not use any lubricant in the water because that would be undesirable to the person swimming in the water.
Now, I think Dick's suggestion of putting a drop of oil on the shaft is a great idea. That can't hurt at all and I'll probably start using that practice myself!