I would recommend looking into mag-drive pumps, as those prior to me have also said.
I have had success with Goulds 3298, Innomags, and even Sundyne ANSI-Mags. All mag-drive pumps, each with their own pros and cons. At this time I don't have an opinion of one over the other, as I have the 3298's in HCl service, the Innomags in NaOH, and NaOCl service and the ANSI-Mag in H2SO4 service. I would also take a look at IWAKI M Series mag-drive pumps and also possibly UltraChem. I haven't had any experience with those, but they are likely worth looking into as it is always good to have options to compare. Good luck.