Recent experimental results have shown that adding nanoparticles inside a bulk material can enhance the thermoelectric performance by reducing the thermal conductivity and increasing the Seebeck coefficient. In this paper we investigate electron scattering from nanoparticles using different models. We compare the results of the Born approximation to that of the partial-wave method for a single nanoparticle scattering. The partial-wave method is more accurate for particle sizes in the 1 nm to 5 nm range where the point scattering approximation is not valid. The two methods can have different predictions for the thermoelectric properties such as the electrical conductivity and the Seebeck coefficient. To include a random distribution of nanoparticles, we consider an effective medium for the electron scattering using the coherent potential approximation. We compare various theoretical results with the experimental data obtained with ErAs nanoparticles in an InGaAlAs matrix. Reasonably good agreement is found between the measured and theoretical electrical conductivity and Seebeck data in the 300 K to 850 K temperature range.