SB,
you would need two files for the import:
1. A pow file with all the time series
2. Another file (trp, shp, ...) with the coordinates of the wells and the corresponding time-series (powerfunction) ID.
First import the time-series (powerfunctions). The import of the wells then can be done with Assign - Database - Import powerfunction ID - Well BC - Automatic (FEFLOW 5.4) or by linking the loaded map file (trp, shp, ...) to the well boundary condition and applying the 'Neighborhood Relationship' regionalization.
Please note that in FEFLOW 5.4 you should not have more than one well in the vicinity of the same node. At import, you would get the pumping rate only of the last well imported. In FEFLOW 6.0 using the Neighborhood Relationship, you can choose to sum the pumping rates of all neighboring well onto the closest mesh node.
BR
Peter