Your rings are rather too small for the pole size, but apply silicone lubricant and it will make a considerable difference. Spray can from the likes of Screwfix. Avoid waxes and furniture polish as they collect the dust and make thing worse in the long term!
This has been really useful. My wife was talking about getting replacement curtains for a bedroom of that kind. I’ve just shown her the video and we are keeping the ones we have got!!!