Unless your grass is astroturf short, it's going to be hard on components. You're just drawing more amps because of the extra load put on your electronics. However, from what I've seen, if ESC temps are high and motor temps are low and everything is rated for a similar amount of power, a bigger pinion should help reduce temperatures slightly.
Your motor appears to be rated for 130A, which would explain why it's not getting as hot as the ESC. 58c really isn't too bad for a motor (136.4F for me lol), but the ESC is getting dangerous at 74c. I'd think you need a higher power ESC if you're going to be running on grass with a 3 cell.
If you do go with a stouter ESC, you will probably find that the motor will start running hot as well. You'll just get a little more time before it gets too hot.