You can try googling "ceramic bearings". But in the 1" size you might only find automotive form factors versus the go kart stuff with the allen set screw. Most solar/battery karts use bicycle tires, which have hubs with a LOT of low resistance bearing options. Just open you wallet. Solar = light weight != 1 inch axle is what I am trying to say.
The tricky thing with the 1" size is for most high performance means long lasting as well, which will have some heft to it because of the weight it has to support. As well as an initial stiffer rolling resistance out of the box. I wonder if you could do some trickery and remove the bearing grease and put in 0W oil. haha. It'll work great for a few laps.
I agree that bike tires would be best, unfortunately the rules forbid that. Believe it or not, changing to the 1" axle is actually saving us weight ha.