In a bowl, whisk together olive oil, soy sauce, Worcestershire sauce, garlic powder, onion powder, paprika, salt, and pepper.
Add the steak cubes and shrimp to the marinade, tossing to coat. Cover and refrigerate for at least 30 minutes or up to 2 hours for more flavor.
Preheat the grill to medium-high heat. If using wooden skewers, soak them in water for 30 minutes to prevent burning.
Thread the marinated steak, shrimp, bell peppers, and onion onto the skewers, alternating between the ingredients.
Place the skewers on the grill and cook for 8-10 minutes, turning occasionally, until the steak is cooked to your desired doneness and the shrimp are pink and opaque.
Remove from the grill and let rest for a few minutes before serving.