I'd try rubber traction grips or rubber talon grips, they stick on over the existing grip texture.

Example: Tractiongrips rubber grip tape overlay for Taurus Millennium G2, G2C, G3C grips 722698953696 | eBay

 

The other options are getting a holster with a shield that keeps the grip off your body, or using sandpaper or something similar to smooth down the grip texture just a bit.

 

I put Talon grips on almost all of my pistols and highly recommend them.

 

Just bought a new G3c and like most everything except the grips are a little rough on my skin. I carry aiwb and here in south texas most of us wear t-shirts and shorts. With nothing under the T-shirt the G3c grips irritate my side any suggestions welcome.

Talon grip wrap. Go with rubber or "Pro". The sandpaper grip will be worse than the stock G2C/G3C grip texture.

 

I like the Hogue Beavertail grips but they apparently aren't making them for the G3. You might contact them to see if/when they will make one for it. The Handall is suggested now for them.

Beavertail Grip Sleeves - HandALL Grip Sleeves - Handgun Grips - Hogue Products

www.hogueinc.com