Yes, Miguel Gallardo is currently the highest ranked player from Mexico at #203. There are quite a few of them on the tour right now, but none have broken through to the ATP level.
Alejandro Hernandez, now just below Gallardo, outside top-200 was ranked as high as #125 about 7 years back as a 20 year old. Pity that he did not go higher.
As for Pancho Gonzales, he was born in South Central Los Angeles as Richard (or Ricardo) Gonzales. "Pancho" was a nickname .. Here is a nice bio page,