Gather the parts into an array using Instance:GetChildren and the players into an array using Players:GetPlayers. Iterate through the array of players, continuing onto the next iteration if their character is unavailable using the continue keyword, then select a random part from the array of parts using the following code:
local part = table.remove(parts, math.random(#parts))
Finally, use Model:PivotTo on the player's character and pass in the part's CFrame