Bring a large pot of well-salted water to a boil over high heat.
Meanwhile, combine the pancetta and oil in a 12-inch nonstick skillet. Cook, stirring, over medium heat until the pancetta is just turning golden, 4 minutes. Add the onion and cook, stirring often, until golden brown, 5 to 8 minutes. Add the shrimp and cook, stirring, until pink and opaque, 1 to 2 minutes. Set aside off the heat.
Cook the linguine in the boiling water according to package directions until al dente, adding the peas in the last minute or two of cooking. Reserve about 1/2 cup of the cooking water and then drain the pasta and peas.
Return the skillet to low heat, add the pasta, peas, and 1/4 cup cooking water. Toss, adding more water if the pasta seems dry. Season to taste with salt and pepper and serve.