I'll tackle the 3D case. I am using the SI system. It should be noted that the electrical resistance of an electrical element (in given case a homogeneous medium) measures its opposition to the passage of an electric current (in given case direct current). The resistance of a homogeneous medium between two electrodes is defined as $$R=\frac{U}{I}=\frac{\rho\epsilon_0}{C}$$ where C is a capacitance between two electrodes.
Let's start with the assumption that instead of two points we have two conducting tiny spheres with a radius $r_0$. The distance between the centers of the spheres is $d$ and $r_0<<d$. To simplify the calculation let us assume that the charge on the spheres is distributed spherically symmetric. Then $$C=2\pi\epsilon_0r_0$$ Finally, required resistance:
$$R=\frac{\rho}{2\pi r_0}$$
