Soak the bread in water to cover for 5 minutes. Squeeze out the extra water.
In a large bowl, combine the three meats, bread, eggs, ¼ cup of the Pecorino, all the Parmesan, ½ cup of the parsley, the nutmeg, and ¼ cup of the olive oil. Season the mixture well with salt and pepper; then mix together gently with your hands. Form the mixture into 3-inch balls. Place them on a baking sheet, cover and refrigerate for at least 1 hour, or as long as overnight, to allow the flavors to blend.
In a 12-inch heavy bottomed skillet, heat the remaining ¼ cup olive oil over high heat until almost smoking. Add the meatballs in batches and brown on all sides. Transfer the meatballs as they’re done to a baking sheet. When they’re all browned drain off the oil.
Add the wine to the pan and deglaze, scraping up all of the browned bits from the meatballs stuck to the bottom of the pan. Add the tomato sauce. Bring to a vigorous simmer and place the meatballs in the sauce. Bring to a boil, then lower the heat and simmer gently for 30 minutes, covered.
Transfer to a platter and serve with the remaining Pecorino and parsley sprinkled over the top.