Everything in the solar system is pretty much made out of the same stuff. There is uranium on Earth, the Moon, and Mars, so we can reasonably expect it to be present on other less massive objects in the solar system.
But you also have to consider that materials stratify based on their density and chemical affinity. The Goldschmidt classification of an element defines sort of chemical cliques for the elements.
Lithophile elements like to oxidize into minerals and float on top of any dense metal core. For instance, the dominant aluminum ore bauxite is frequently found close to the surface of the earth. To find those elements in space, you look for a rock-dominant (oxidized) asteroid.
Siderophile elements like to form solid solutions with iron, and may not oxidize to lighter minerals readily. Elements like gold and platinum are considered rare on Earth not because the planet does not have a great quantity of them, but because the vast majority of that mass is way down in the iron core, where we cannot yet reach it. The mass near the surface is only there due to quirks of geology. To find those elements in space, you look for a metals-dominant asteroid.
Chalcophile elements like sulfur, and on Earth their rarity (in terms of the amount we can dig up) is between lithophiles and siderophiles, because they tend to stratify above the iron-lovers and below the oxygen-lovers.
The only elements that may be difficult to find would be those that form volatile molecules, because they typically get gradually blown away by solar wind, or stripped away all at once by a catastrophic cosmic event.
Uranium and thorium are lithophile elements, so they shouldn't be too difficult to find on rocky, oxygen-heavy asteroids. Just look for low albedo and alpha particles from pitchblende. But beware that absent the ore-concentrating processes of large planets, you may have to process a lot of rock to get a usable quantity of fissile elements.