  We report the successful growth and the impurity scattering effect of single
crystals of Na(Fe$_{0.97-x}$Co$_{0.03}$T$_x$)As (T=Cu, Mn). The temperature
dependence of DC magnetization at high magnetic fields is measured for
different concentrations of Cu and Mn. Detailed analysis based on the
Curie-Weiss law indicates that the Cu doping weakens the average magnetic
moments, while doping Mn enhances the local magnetic moments greatly,
suggesting that the former may be non- or very weak magnetic impurities, and
the latter give rise to magnetic impurities. However, it is found that both
doping Cu and Mn will enhance the residual resistivity and suppress the
superconductivity at the same rate in the low doping region, being consistent
with the prediction of the S$^{\pm}$ model. For the Cu-doped system, the
superconductivity is suppressed completely at a residual resistivity $\rho_0$ =
0.87 m$\Omega$ cm at which a strong localization effect is observed. However,
in the case of Mn doping, the behavior of suppression to \emph{T}$_{c}$ changes
from a fast speed to a slow one and keeps superconductive even up to a residual
resistivity of 2.86 m$\Omega$ cm. Clearly the magnetic Mn impurities are even
not as detrimental as the non- or very weak magnetic Cu impurities to
superconductivity in the high doping regime.
