Stir the masa harina and water together in a mixing bowl until smooth; knead well. Cover bowl, and let the dough rest 5 to 10 minutes.
Shape the dough into eight, 2 inch diameter balls. On a lightly floured surface, roll out each ball into 6 inch diameter round. Sprinkle 1/4 cup queso fresco over each round. Place a second tortilla over the cheese, and pinch the edges together to seal in the cheese.
Heat ungreased skillet over medium-high heat. Place one tortilla into the skillet at a time, and cook until cheese melts and tortillas are lightly browned, about 2 minutes on each side.
