Heat the oil in a large non-stick skillet or paella pan over medium-high heat. Add the onion, bell peppers, and garlic, and cook, stirring occasionally, until the vegetables are tender, about 8 minutes.
Add the tomato paste and saffron to the skillet, stirring until well mixed. Add the quinoa, broth, tomatoes, and salt; bring to a boil. Reduce the heat to medium-low. Cover and simmer until the liquid is absorbed and the quinoa is tender about 20 minutes.
Tuck the shrimp and calamari into the quinoa mixture. Cover and cook until the shrimp and calamari are cooked through, about 5 minutes. Remove from the heat; sprinkle with parsley and garnish with lemon wedges.