I agree with Wonderwhippet and Sarzak that this is a Spanish copy of the Model 1910 FN/Browning.
During the years from WWI until the Spanish Civil War there were literally hundreds of small gun makers in the Eibar Region of Spain.....it was virtually a cottage industry. They turned out copies of various early Browning design automatics as well as copies of various Colt & S&W revolvers.
They varied in quality, but all have one thing in common......almost none of them had parts that would interchange......and none of them have parts that are available today.
I'm afraid that your chances of finding grips for this gun are slim to none.....soooooooo....I'd suggest that you find some nice wood and start whittling.