Preheat your oven to 375°F (190°C). Line a muffin tin with paper liners or grease it lightly.
In a large bowl, whisk together the flour, sugar, baking powder, baking soda, and salt.
In another bowl, mix the milk, vegetable oil, vanilla extract, and eggs until well combined.
Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix.
Fold in the diced pears gently.
Divide the batter evenly among the muffin cups, filling each about ⅔ full.
Bake for 20-25 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Let the muffins cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.